Composite coating as well as preparation method and application thereof

Abstract

The invention discloses a composite coating as well as a preparation method and application thereof, and relates to the technical field of composite coatings. The invention provides a composite coating. The composite coating comprises a porous base membrane layer, an aramid nanofiber layer and a rigid coating which are arranged in sequence. According to the composite coating provided by the invention, the aramid nanofiber layer is used as a mechanical transition layer of the rigid coating and the flexible porous base membrane layer, interface regulation and control are carried out to realize a stable interface structure of the flexible porous base membrane layer and the rigid coating, and the problems of separation of the rigid coating and the flexible porous base membrane layer and the like are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of composite coatings, in particular to a composite coating and a preparation method and application thereof. Background Art

[0002] With the rapid development of electronic technology, significant advantages such as lightweight, bendability and durability have gradually become an important development direction that has attracted much attention in the electronics industry. In cutting-edge fields such as wearable technology, electronic displays and smart sensors, such devices have shown great application potential and broad development prospects. However, current flexible electronic devices mainly rely on expensive and complex material systems such as polyimide and conductive polymers, which seriously restricts their large-scale commercialization process. Polyolefin materials are ideal materials for flexible electronic device substrates due to their excellent mechanical properties, good chemical stability and significant cost-effectiveness. However, traditional polyolefin materials still face many technical challenges in flexible electronic applications, mainly manifested in poor thermal stability and insufficient interfacial bonding with other functional coatings. These problems seriously hinder their widespread application in the field of flexible electronics.

[0003] Poly(p-phenylene terephthalamide) (PPTA), also known as para-aramid fiber (Kevlar), was originally developed and produced by Dupont in the United States in the 1960s and 1970s. PPTA is a rigid liquid crystal polymer with excellent thermal stability and mechanical properties. For example, in Chinese patents such as CN104993089A and CN107452921A, there have been extensive reports on the use of PPTA to improve the heat resistance of polyolefin-based diaphragms for lithium batteries. However, there is no report on the method of using PPTA as a transition layer to form a firm interface structure between a rigid coating and a flexible base film. In addition, the para-aramid coating technology proposed in the Chinese patent application number 201510453815.X and the Japanese patent application number 2010-254731 requires the addition of an adhesive to achieve the effect of interfacial bonding between aramid and polyolefin composite films. In Chinese patent CN 111883777A, plasma cleaning is required to ensure that the metal coating has sufficient adhesion to the substrate.

[0004] Therefore, how to improve the performance of polyolefin materials to better meet the needs of flexible electronic devices has become a key issue that needs to be solved in the current technical field. In view of this, this application is proposed. Summary of the invention

[0005] Based on this, the purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a composite coating and a preparation method and application thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a composite coating, which includes a porous base film layer, an aramid nanofiber layer, and a rigid coating arranged in sequence; the porous base film layer is a porous base film layer with a pore structure formed by polyolefin fibers; the aramid nanofiber layer is an aramid nanofiber layer with a pore structure formed by aramid nanofibers; the component of the rigid coating is at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide, and titanium oxide.

[0007] Preferably, the thickness of the porous base film layer is 0.1 - 10 μm, the pore diameter of the porous base film layer is 20 - 80 nm, and the porosity is 30 - 60%; the diameter of the polyolefin fiber is 30 - 60 nm;

[0008] And / or, the thickness of the aramid nanofiber layer ≥ 0.05 μm, the pore diameter of the aramid nanofiber layer is 20 - 80 nm, and the porosity is 10 - 50%; the diameter of the aramid nanofiber is 10 - 50 nm;

[0009] And / or, the thickness of the rigid coating is 0.01 - 1 μm.

[0010] Preferably, the pore diameter of the porous base film layer is 30 - 40 nm, and the porosity is 35 - 50%; the diameter of the polyolefin fiber is 45 - 55 nm.

[0011] Preferably, the pore diameter of the aramid nanofiber layer is 30 - 50 nm, and the porosity is 30 - 40%; the diameter of the aramid nanofiber is 20 - 30 nm.

[0012] The present invention utilizes the deprotonation + reprotonation process of aramid fibers, enabling the aramid nanofiber layer to form entanglement and nano-confinement effects with the flexible porous base film layer, solving the problem that existing aramid nanofibers and porous base films require the addition of adhesives or surface treatment to achieve interfacial bonding. The present invention provides a composite coating, using the aramid nanofiber layer as a mechanical transition layer between the rigid coating and the flexible porous base film layer, and performing interfacial regulation to achieve a stable interfacial structure between the flexible base film layer and the rigid coating, effectively solving problems such as the separation of the rigid coating and the flexible base film layer.

[0013] Preferably, the thickness of the porous base film layer is 2 - 5 μm; and / or, the thickness of the aramid nanofiber layer is 0.2 - 1 μm; and / or, the thickness of the rigid coating is 0.05 - 0.5 μm.

[0014] Further preferably, the thickness of the porous base film layer is 2.5 - 4 μm.

[0015] Preferably, the raw material of the porous base film layer is a film layer with a porous structure formed by polyolefin fibers; the polyolefin is at least one of polypropylene and polyethylene; more preferably, the polyolefin is polyethylene.

[0016] Preferably, the raw material of the film layer with a porous structure formed by polyolefin fibers can be a commercially available product or can be prepared by oneself. Specifically, it can be prepared by wet or dry stretching methods.

[0017] Preferably, the preparation method of the raw material of the film layer with a porous structure formed by polyolefin fibers is as follows: adding a polyolefin-based polymer and a lubricant into a twin-screw extruder, co-extruding and gelating to form a gel sheet, then stretching it into a polyolefin fiber ultra-thin film through a biaxial stretching process, and finally preparing a polyolefin-based thin film material, that is, the film layer with a porous structure formed by polyolefin fibers, through treatments such as extraction and annealing. The stretching ratio is (5 - 20)×(5 - 20).

[0018] Preferably, the thickness of the raw material of the film layer with a porous structure formed by polyolefin fibers prepared is (0.1 - 5)±0.5 μm.

[0019] Preferably, the present invention also provides a preparation method of the composite coating, including the following steps:

[0020] S1. Mixing aramid fibers, an alkaline solution, and an organic solvent evenly to obtain an aramid nanofiber dispersion;

[0021] S2. Coating the aramid nanofiber dispersion on the surface of the porous base film layer, annealing, soaking it in a mixed solution, washing with water and drying, and then placing it in a magnetron sputtering device to obtain the composite coating.

[0022] The inventor found in the actual experiment process that there is mutual entanglement between the porous base film layer and the aramid nanofiber layer, and between the aramid nanofiber layer and the rigid coating in the composite coating. During the annealing process, the combined action of the solvent volatilization of aramid nanofibers (ANF) and the partial melting of the polyolefin chains of the porous base film promotes the rapid diffusion of polyolefin molecular chains to the surface of adjacent ANF and mutual entanglement, thereby forming a firm interfacial interlock between ANF and the polyolefin substrate. In addition, the particles after magnetron sputtering and the ANF with a high specific surface area are bonded through the nanoconfinement effect (physical adsorption) and by forming a coordination structure with nitrogen (N) and oxygen (O) elements on ANF, further improving the stability of the coating. At the same time, the present invention uses the aramid nanofiber layer (elastic modulus 40 - 60 GPa) as a mechanical transition layer between the rigid coating (elastic modulus > 50 GPa) and the flexible base film layer (elastic modulus < 30 GPa), forming a gradient modulus interface to reduce the interfacial stress concentration, effectively solving the problem of the separation of the rigid coating and the flexible base film layer under dynamic mechanical action, and significantly improving the interfacial stability of the material.

[0023] In the actual research process of the inventor, it is found that the pore size distribution and porosity characteristics of the porous base film layer of the finally prepared composite coating are synergistically regulated by the annealing temperature and the magnetron sputtering power. Research shows that within a suitable temperature range, the thermal activation effect can promote the migration and rearrangement of polyolefin chains, and significantly enhance the interfacial bonding strength by forming a topological entanglement structure with aramid nanofibers. In addition, increasing the magnetron sputtering power can improve the bonding between rigid nanoparticles and aramid nanofibers. However, when the process parameters exceed the critical threshold, the melting phenomenon of the substrate caused by overheating will damage the integrity of the porous structure.

[0024] Preferably, in the step S1, at least one of the following (1)-(4) is satisfied:

[0025] (1) The aramid fiber is para-aramid fiber or meta-aramid fiber;

[0026] (2) The mass-volume ratio of the aramid fiber, the alkaline solution, and the organic solvent is (0.1-2) g:(3-20) mL:100 mL;

[0027] (3) The alkaline solution is a mixed solution of an alkali and a proton donor, and the mass-volume ratio of the alkali and the proton donor is (0.1-10) g:(2-20) mL;

[0028] (4) The organic solvent is at least one of dimethyl sulfoxide and dimethyl fumarate.

[0029] Preferably, the alkali is at least one of sodium hydroxide and potassium hydroxide; the proton donor is at least one of water, ethanol, isopropanol, ethylene glycol, propylene glycol, and butanediol.

[0030] Preferably, the meta-aramid fiber, such as (DuPont), (Teijin, Japan), (Taihe New Materials, China); the para-aramid fiber, such as (DuPont), (Teijin, Japan), (Taihe New Materials, China);

[0031] Preferably, the aramid fiber is Kevlar fiber, purchased from DuPont.

[0032] Further preferably, the alkali is potassium hydroxide.

[0033] Preferably, in the step S2, at least one of the following (5)-(9) is satisfied:

[0034] (5) The annealing temperature is 100-130 °C, and the annealing time is 10-20 min;

[0035] (6) The mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is (0.1 - 0.5):1;

[0036] (7) The soaking time is 5 - 30 min;

[0037] (8) The vacuum degree of the magnetron sputtering is 10 -4 Pa, the coating power of the magnetron sputtering is 5 - 200 W, and the magnetron sputtering time is 20 - 1500 s;

[0038] (9) The target for the magnetron sputtering is at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide, and titanium oxide.

[0039] Further preferably, the annealing temperature is 120 - 130 °C.

[0040] Further preferably, the soaking time is 10 - 20 min.

[0041] Further preferably, the coating power of the magnetron sputtering is 25 - 100 W, and the magnetron sputtering time is 50 - 300 s.

[0042] In addition, the present invention provides an application of the composite coating in the preparation of flexible electronic devices; specifically, the present invention discloses an application of the composite coating in the preparation of wearable sensors, electronic skins, and flexible displays.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: The operation steps of the present invention are simple, and the process equipment has the possibility of realizing large-scale and continuous production. By utilizing the deprotonation + reprotonation process of aramid fibers, the aramid nanofiber layer and the flexible porous substrate layer form entanglement and nano-confinement effects, solving the problem that the existing aramid fibers and porous substrates need to add adhesives or surface treatment to achieve interfacial bonding. The present invention provides a composite coating, using the aramid nanofiber layer as a mechanical transition layer between the rigid coating and the flexible porous substrate layer, and performing interfacial regulation to achieve a stable interfacial structure between the flexible porous substrate layer and the rigid coating, effectively solving problems such as the separation of the rigid coating and the flexible substrate layer. Description of the Drawings

[0044] Figure 1 Scanning electron micrograph of the composite coating prepared in Example 1. Detailed Embodiments

[0045] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. The experimental reagents and instruments designed in the embodiments and comparative examples of the present invention are all common ordinary reagents and instruments unless otherwise specified, and can be obtained from commercial channels. In the embodiments and comparative examples, the experimental methods used are all conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0046] Examples and Comparative Examples

[0047] Examples 1-16

[0048] Example 1

[0049] A composite coating, comprising a porous base film layer, an aramid nanofiber layer and a rigid coating arranged in sequence; the raw material of the porous base film layer is a film layer with a pore structure formed by polyolefin fibers, that is, a polyethylene porous film, with a pore diameter of 40 nm, a porosity of 55±5%, and a thickness of 2.5±0.5 μm (purchased from Guangzhou Guna Technology Co., Ltd.);

[0050] The preparation method of the composite coating comprises the following steps:

[0051] (1) Mix Kevlar fibers, an alkaline solution and an organic solvent evenly to obtain an aramid nanofiber dispersion;

[0052] The preparation of the alkaline solution: The alkaline solution is a mixed solution of KOH and a proton donor. Mix KOH and the proton donor at 60°C for 5 minutes and mix evenly to obtain the alkaline solution; the mass-volume ratio of KOH to the proton donor is 0.3 g: 3 mL; the proton donor is ethylene glycol;

[0053] The mass-volume ratio of the Kevlar fibers, the alkaline solution and dimethyl sulfoxide is 0.5 g: 3 mL: 100 mL; the Kevlar fibers, the alkaline solution and dimethyl sulfoxide are stirred and mixed evenly in a stirring device (magnetic stirrer), the stirring temperature is 60°C, and the reaction time is 10 minutes;

[0054] (2) Under nitrogen protection, coat the aramid nanofiber dispersion on the surface of the porous base film layer, anneal at 130°C for 10 minutes, then soak in a mixed solution for 10 minutes, wash with water and dry, and then place it in a magnetron sputtering device to obtain the composite coating; the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.2:1; in the magnetron sputtering device, adjust the vacuum degree to 10-4 Pa, processed in an argon atmosphere. The target is copper, the coating power is 25 W, and the time is 300 s.

[0055] Example 2

[0056] Compared with Example 1, only the volume ratio of the mixed solution is different. Specifically, the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.5:1.

[0057] Example 3

[0058] Compared with Example 1, only the power and time of the magnetron sputtering are different. Specifically, the coating power is 100 W and the time is 75 s.

[0059] Example 4

[0060] Compared with Example 1, only the power and time of the magnetron sputtering are different. Specifically, the coating power is 10 W and the time is 750 s.

[0061] Example 5

[0062] Compared with Example 1, only the power and time of the magnetron sputtering are different. Specifically, the coating power is 200 W and the time is 37.5 s.

[0063] Example 6

[0064] Compared with Example 1, only the soaking time is different, and the soaking time is 20 min.

[0065] Example 7

[0066] Compared with Example 1, only the soaking time is different, and the soaking time is 5 min.

[0067] Example 8

[0068] Compared with Example 1, only the annealing temperature is different, and it is annealed at 100 °C for 20 min.

[0069] Example 9

[0070] Compared with Example 1, only the thickness of the base film layer is different. The raw material of the porous base film layer is a polyethylene porous membrane, with a pore size of 35 nm, a porosity of 45 ± 5%, and a thickness of 5 ± 0.5 μm (Guangzhou Guna Technology Co., Ltd.).

[0071] Example 10

[0072] Compared with Example 1, only the components of the alkaline solution are different, which is a mixed solution of KOH and water.

[0073] Example 11

[0074] Compared with Example 1, only the target material is different. The target material is silver.

[0075] Example 12

[0076] Compared with Example 1, only the aramid fiber is different. It is Nomex fiber, purchased from DuPont.

[0077] Example 13

[0078] Compared with Example 1, only the mass-volume ratio of the aramid fiber, alkaline solution, and organic solvent is different, which is 2 g: 15 mL: 100 mL.

[0079] Example 14

[0080] Compared with Example 1, only the alkaline solution is a mixture of an alkali and a proton donor, and the mass-volume ratio of the alkali and the proton donor is different, which is 5 g: 15 mL;

[0081] Example 15

[0082] Compared with Example 1, only the thickness of the aramid nanofiber layer is different; by changing the addition amount of the aramid nanofiber dispersion liquid during the coating process.

[0083] Example 16

[0084] Compared with Example 1, only the thickness of the rigid coating is different; by changing the magnetron sputtering time.

[0085] Comparative Examples 1-11

[0086] Comparative Example 1

[0087] Compared with Example 1, only the annealing treatment is not carried out in the preparation process, and the solution is directly soaked as follows:

[0088] A composite coating, comprising a porous base film layer, an aramid nanofiber layer, and a rigid coating arranged in sequence;

[0089] The preparation method of the composite coating includes the following steps:

[0090] (1) Mix Kevlar fiber, alkaline solution, and organic solvent evenly to obtain an aramid nanofiber dispersion liquid;

[0091] The preparation of the alkaline solution: The alkaline solution is a mixture of KOH and a proton donor. Mix KOH and the proton donor at 60 °C for 5 minutes and mix evenly to obtain the alkaline solution; the mass-volume ratio of KOH and the proton donor is 0.3 g: 3 mL; the proton donor is ethylene glycol;

[0092] The mass-volume ratio of the Kevlar fiber, alkaline solution, and dimethyl sulfoxide is 0.5 g: 3 mL: 100 mL; the Kevlar fiber, alkaline solution, and dimethyl sulfoxide are stirred and mixed evenly in a stirring device (magnetic stirrer), the stirring temperature is 60 °C, and the reaction time is 10 min;

[0093] (2) Under nitrogen protection, the aramid nanofiber dispersion is coated on the surface of the porous base film layer, and then immersed in the mixed solution for 10 min. After washing with water and drying, it is placed in a magnetron sputtering device to obtain the composite coating; the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.2:1; the raw material of the porous base film layer is a polyethylene porous membrane, with a pore size of 40 nm, a porosity of 55 ± 5%, and a thickness of 2.5 ± 0.5 μm (Guangzhou Guna Technology Co., Ltd.); in the magnetron sputtering device, the vacuum degree is adjusted to 10 -4 Pa, and it is processed in an argon atmosphere. The target material is copper, the coating power is 25 W, and the time is 300 s.

[0094] Comparative Example 2

[0095] Compared with Example 1, only the volume ratio of the mixed solution is different. Specifically, the mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is 0.05:1.

[0096] Comparative Example 3

[0097] Compared with Example 1, only the mixed solution is a mixture of water and ethanol, and the volume ratio of water to ethanol is 0.2:1.

[0098] Comparative Example 4

[0099] Compared with Example 1, only the power and time of the magnetron sputtering are different. Specifically, the coating power is 250 W and the time is 30 s.

[0100] Comparative Example 5

[0101] Compared with Example 1, the annealing temperature and time are different. Specifically, annealing is carried out at 80 °C for 20 min.

[0102] Comparative Example 6

[0103] Compared with Example 1, only the soaking treatment is not carried out in the preparation process, specifically as follows:

[0104] A composite coating, comprising a porous base film layer, an aramid nanofiber layer, and a rigid coating arranged in sequence;

[0105] The preparation method of the composite coating includes the following steps:

[0106] (1) Mix Kevlar fibers, an alkaline solution, and an organic solvent evenly to obtain an aramid nanofiber dispersion;

[0107] Preparation of the alkaline solution: The alkaline solution is a mixed solution of KOH and a proton donor. Mix KOH and the proton donor at 60 °C for 5 min and mix evenly to obtain the alkaline solution; the mass-volume ratio of KOH to the proton donor is 0.3 g: 3 mL; the proton donor is ethylene glycol;

[0108] The mass-volume ratio of the Kevlar fibers, the alkaline solution, and dimethyl sulfoxide is 0.5 g: 3 mL: 100 mL; the Kevlar fibers, the alkaline solution, and dimethyl sulfoxide are stirred and mixed evenly in a stirring device (magnetic stirrer), the stirring temperature is 60 °C, and the reaction time is 10 min;

[0109] (2) Under nitrogen protection, coat the aramid nanofiber dispersion on the surface of the porous base film layer, anneal at 130 °C for 10 min, wash with water and dry, and then place it in a magnetron sputtering device to obtain the composite coating; the raw material of the porous base film layer is a polyethylene porous membrane, with a pore size of 40 nm, a porosity of 55 ± 5%, and a thickness of 2.5 ± 0.5 μm (Guangzhou Guna Technology Co., Ltd.); in the magnetron sputtering device, adjust the vacuum degree to 10 -4 Pa, and perform treatment in an argon atmosphere. The target is copper, the coating power is 25 W, and the time is 300 s.

[0110] Comparative Example 7

[0111] Compared with Example 1, it does not contain an aramid nanofiber layer. Specifically: Place the polyethylene porous membrane in a magnetron sputtering device, adjust the vacuum degree to 10 -4 Pa, and perform treatment in an argon atmosphere to obtain the composite coating; the target is copper, the coating power is 25 W, and the time is 300 s; the raw material of the porous base film layer is a polyethylene porous membrane, with a pore size of 40 nm, a porosity of 55 ± 5%, and a thickness of 2.5 ± 0.5 μm (Guangzhou Guna Technology Co., Ltd.).

[0112] Comparative Example 8

[0113] Compared with Example 1, it does not contain an aramid nanofiber layer. Specifically: Place the polyethylene porous membrane in a magnetron sputtering device, adjust the vacuum degree to 10 -4 Pa, and perform treatment in an argon atmosphere to obtain the composite coating; the target is copper, the coating power is 100 W, and the time is 75 s; the raw material of the porous base film layer is a polyethylene porous membrane, with a pore size of 40 nm, a porosity of 55 ± 5%, and a thickness of 2.5 ± 0.5 μm (Guangzhou Guna Technology Co., Ltd.).

[0114] Comparative Example 9

[0115] Compared with Example 1, the thickness of the aramid nanofiber layer is different; by changing the addition amount of the aramid nanofiber dispersion during the coating process.

[0116] Comparative Example 10

[0117] Compared with Example 1, the thickness of the rigid coating is different; by changing the magnetron sputtering time.

[0118] Comparative Example 11

[0119] Compared with Example 1, the thickness of the rigid coating is different; by changing the magnetron sputtering time.

[0120] The structural parameters of the aramid nanofiber layer and the rigid coating in the composite coatings prepared in the examples and comparative examples of the present invention are shown in Table 1 below. Among them, the fiber diameter and pore size are obtained by SEM testing; the porosity is determined by a simple gravimetric method and calculated according to the thickness and density of the corresponding material layer. Among them, the fiber diameter and pore size are both average values;

[0121] The thickness is obtained by using a Mar thickness gauge.

[0122] Table 1

[0123]

[0124]

[0125]

[0126] Performance Test

[0127] (1) The peel strength of the composite coating materials prepared in the examples and comparative examples was tested: tested by a tensile machine. Take a test sample with a size of 15×100 mm, stick the tape on the stainless steel plate, then stick the measurement sample evenly on the double-sided tape, use a 1 kg standard small pressure roller to squeeze back and forth 3 times, then stick the tape on the sample surface, use a 1 kg standard small pressure roller to squeeze back and forth 3 times, and then take the pressed sample to the tensile machine for 180° stretching at a speed of 100 mm / min, and the result takes the maximum value.

[0128] (2) The resistance of the composite coating materials prepared in the examples and comparative examples was tested: tested by using a flexible electronic tester. Take a test sample with a size of 10×30 mm, and fix both ends of the test sample on both sides of the folding test fixture of the flexible electronic tester with tape. Set the folding parameters of the flexible electronic tester to an initial angle of 0°, a folding angle of 180°, a folding rate of 40° / second, the number of folding times of 10,000 times and 100,000 times, and a folding radius of 0.3 mm. After folding, use a milliohm meter to test the resistance of the sample, and the result takes the maximum value.

[0129] The test results are shown in Table 2 below.

[0130] Table 2

[0131]

[0132]

[0133] As can be seen from the above table, a composite coating provided by the present invention can effectively improve the interfacial bonding force between the rigid coating and the flexible base film layer, thereby solving problems such as interfacial separation during the dynamic deformation process and meeting the requirements of flexible electronic device applications. Figure 1 It is a scanning electron microscope image of the composite coating prepared in Example 1. Metal particles are coated on aramid nanofibers to form a stable deposition, realizing a fibrous conductive network structure, enabling the material to have a stable gradient mechanical interface and thus maintaining excellent electrical conductivity under extreme dynamic mechanical behaviors.

[0134] Because the magnetron sputtering power was too high, the kinetic energy of high-energy particles was converted into heat, resulting in the rupture of the composite coating prepared in Comparative Example 4, and no subsequent tests were carried out.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite coating, characterized in that: It includes a porous base membrane layer, an aramid nanofiber layer and a rigid coating layer arranged in sequence; the porous base membrane layer is a porous base membrane layer with a pore structure formed by polyolefin fibers; the aramid nanofiber layer is an aramid nanofiber layer with a pore structure formed by aramid nanofibers; the rigid coating layer is composed of at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide and titanium oxide.

2. The composite coating according to claim 1, characterized in that The thickness of the porous base membrane layer is 0.1-10 μm, the pore size of the porous base membrane layer is 20-80 nm, and the porosity is 30-60%; the diameter of the polyolefin fiber is 30-60 nm; And / or, the thickness of the aramid nanofiber layer is ≥ 0.05 μm, the pore size of the aramid nanofiber layer is 20-80 nm, the porosity is 10-50%; the diameter of the aramid nanofiber is 10-50 nm; And / or, the rigid coating has a thickness of 0.01-1 μm.

3. The composite coating according to claim 2, characterized in that The pore size of the porous base membrane layer is 30-40nm, and the porosity is 35-50%; the diameter of the polyolefin fiber is 45-55nm.

4. The composite coating according to claim 2, characterized in that The pore size of the aramid nanofiber layer is 30-50nm, and the porosity is 30-40%; the diameter of the aramid nanofiber is 20-30nm.

5. A method for preparing a composite coating according to any one of claims 1 to 4, characterized in that: The steps include: S1, mixing aramid fiber, alkaline solution and organic solvent uniformly to obtain aramid nanofiber dispersion; S2. Coating the aramid nanofiber dispersion on the surface of the porous base film layer, immersing it in a mixed solution after annealing, washing and drying it, and placing it in a magnetron sputtering device to obtain the composite coating.

6. The method for preparing the composite coating according to claim 5, characterized in that: In step S1, at least one of the following (1)-(4) is satisfied: (1) The aramid fiber is para-aramid fiber or meta-aramid fiber; (2) The mass volume ratio of the aramid fiber, the alkaline solution, and the organic solvent is (0.1-2) g: (3-20) mL: 100 mL; (3) The alkaline solution is a mixture of a base and a proton donor, and the mass volume ratio of the base to the proton donor is (0.1-10) g: (2-20) mL; (4) The organic solvent is at least one of dimethyl sulfoxide and dimethyl fumarate.

7. The method for preparing the composite coating according to claim 6, characterized in that: The base is at least one of sodium hydroxide and potassium hydroxide; the proton donor is at least one of water, ethanol, isopropanol, ethylene glycol, propylene glycol, and butylene glycol.

8. The method for preparing the composite coating according to claim 5, characterized in that: In step S2, at least one of the following (5)-(9) is satisfied: (5) The annealing temperature is 100-130° C. and the annealing time is 10-20 min; (6) The mixed solution is a mixture of dimethyl sulfoxide and isopropanol, and the volume ratio of dimethyl sulfoxide to isopropanol is (0.1-0.5):1; (7) The soaking time is 5-30 min; (8) The vacuum degree of the magnetron sputtering is 10 -4 Pa, the coating power of magnetron sputtering is 5-200W, and the time of magnetron sputtering is 20-1500s; (9) The target material of the magnetron sputtering is at least one of copper, aluminum, platinum, gold, silver, titanium, molybdenum, silicon, aluminum oxide, indium tin oxide, silicon oxide, and titanium oxide.

9. The method for preparing the composite coating according to claim 8, characterized in that: The immersion time is 10-20 minutes; and / or the magnetron sputtering coating power is 25-100W, and the magnetron sputtering time is 50-300 seconds.

10. Use of the composite coating according to any one of claims 1 to 4 in the preparation of flexible electronic devices.

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